The human hand is both a sensory organ through which information is transmitted and received, and a powerful and delicate tool. The field of robotics seeks to design a robotic hand which is equally and dextrous and sensitive as the human hand. Imparting power to a robotic hand is easily accomplished and is well known. Since a robotic hand acts as an amplification of a human hand force, it is capable of grasping capabilities over a wider range than the human hand. With such capability goes the need for: (1) a wide range of grasp force sensitivity, in order to prevent damage to the hand and/or grasped objects, (2) revealing when the object is first grasped; and (3) precise operation in performing delicate tasks.
Past approaches to measuring robotic hand grasp force have focused on the use of cantilevered claws whose rotary deflection was measured. Another prior art approach was to employ mounts whose bending was monitored. Although the rotary or bending motions of these approaches was slight, such motions caused a departure from parallelism of the claws during grasping. Such prior art grasp force sensing and mounting systems, prior to the advent of this invention, were inadequate.